Booster rocket motor

ABSTRACT

An improved booster for a space vehicle or missile and in which the booster employs two types of propellants. The main charge consists of an oxygen-rich mixture cast in the form of a cylinder within the booster and the other charge, which serves as a covering or overlay for the main charge, consists of an oxygenpoor mixture formed as a hollow cylinder. The main charge is therefore rendered immune from combustion by the covering layer so that when oxygen is fed to the interior of the inner cylinder, the oxygen-poor mixture is able to support combustion, and as it burns through its own thickness the main charge becomes uncovered and ignites, due to the presence of the oxygen contained within the main charge. If the booster is one of several, clustered about the space vehicle and fails to ignite upon the introduction of the supplied oxygen, a valve controlled by an explosive bolt in the oxygen supply line is exploded which automatically cuts off the line to all the boosters and terminates the launching operation. In this way, the remaining boosters which might have functioned and therefore could have caused an imbalance of thrust would now have been rendered inactive so that the costly upper stages of the rocket are preserved.

ypes of propellants.

-rich mixture cast in the form of a cylinder within the booster and theother charge,

which serves as a covering or overlay for the main charge, consists ofan oxygen ygen is fed to -poor mixture is through its own nd ignites,

e main charge. If the booster is one of several, clustered about thespace vehicle and fails to ignite upon the introduction of the y cutsoff ing operamight have mbalance of Primary ExaminerSamueI FeinbergAttorneys-Harry A. Herbert, Jr. and Herbert H. Brown ABSTRACT: Animproved booster for a space vehicle or missile and in which the boosteremploys two t The main charge consists of an oxygen -poor mixture formedas a hollow cylinder. The main charge is therefore rendered immune fromcombustion by the covering layer so that when ox the interior of theinner cylinder, the oxygen able to support combustion, and as it burnsthickness the main charge becomes uncovered a 60/280 due to the presenceof the oxygen contained within th 60/251,102/101 F02k 9/06 60/2501supplied oxygen, a valve controlled by an explosive bolt in the 39-47oxygen supply line is exploded which automaticall the line to all theboosters and terminates the launch tion. In this way, the remainingboosters which functioned and therefore could have caused an i 60/251thrust would now have been rendered inactive so that the 60/251 costlyupper stages of the rocket are preserved.

Inventor Albert Ray Osburn Brigham City, Utah 773,362 Oct. 25, 1968Patented Mar 23, 1971 The United States of America as represented by theSecretary of the Air Force 2 Claims, 2 Drawing Figs.

References Cited UNITED STATES PATENTS 3,283,510 11/1966 Mangum et a1.11/1967 Aycock........................

United States Patent [21] Appl.No.

[22] Filed [73] Assignee [54] BOOSTER ROCKET MOTOR 51 [50]FieldofSearch...........................................

Pmmanmeamn Y 3572,0139

IN VENTOR. 1695! 0580A? BOOSTER ROCKET MOTOR BACKGROUND OF THE INVENTIONIn the art of propelling rockets, missiles, etc., into outer space,various kinds of propellants, liquid and solid, contained within therocket are employed. When there is need for thrust power of considerableamount, as in the case of a heavy payload, it is customary to employ anumber of booster rockets symmetrically positioned about the mainrocket. These booster motors are temporarily attached to the main rocketor space vehicle. As the rocket complex is lifted from the pad and gainsproper speed or distance, the added thrust of the booster rocket isterminated, either as a group, or in a predetermined order upon signalfrom the ground and the spent boosters automatically fall away from themain rocket. The latter continues its upward flight by the thrustdeveloped by its own source of power. in the use of booster rockets, itis necessary that the addition of booster power when the spacecraft isactually being launched be accomplished in a strictly symmetrical mannerin order to keep the vehicle pointed in the right direction. Obviously,all the boosters must be ignited simultaneously and in the event thatone should fail, an imbalance of thrust is created which makes itimperative that the operation of all of the boosters should immediatelycease.

SUMMARY OF THE INVENTION An object of the invention is to provide abooster motor for attachment to a space vehicle or missile and in whichthe combustion within the booster can be terminated at will almostimmediately after the propellant in the booster has been ignited.

Another object is to provide a cluster of solid propellant rocketboosters for spacecraft having a heavy payload and in which the boosterscan be rendered simultaneously inoperative prior to the actual mount oflaunch.

These objects are carried out in brief by providing each booster unitwith an auxiliary charge of an oxygen-poor solid propellant and a maincharge of oxygen-rich solid propellant, one covering the other as anoverlay, and then burning the ox ygen-poor charge by introducing oxygenunder strictly controlled conditions in the absence of which theauxiliary charge would not support combustion but would continue tocover and thereby protect the oxygen-rich charge from combustion. Theintroduction of oxygen can be terminated should an emergency arise, andassuming the oxygen-rich propellant has not been ignited in themeantime, the booster is rendered inoperative. The invention will bebetter understood when the following description is perused inconnection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 represent a diagrammatic showingof a spacecraft to which the improved booster motors are attached andstanding poised on a launching pad; and

MG. 2 shows the longitudinal section of one of the booster motors shownin FIG. I, the lower end of the booster having been broken away. Certainancillary apparatus is shown by diagram.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, there isshown by way of diagram a rocket vehicle I typified as a four-stagedevice. The walls or separation between the stages are broadly indicatedat 2, 3 and 4 and the jet nozzles for the respective stages at 5, 6 and7. Two boosters generally indicated at 8, 9 are typically illustrated,located on each side of the rocket vehicle for balance of power reasons,each booster being temporarily attached to the vehicle by a special andwell-known form of fastener lit which allows instant detachment onsignal. The main vehicle and each of the boosters are provided with astreamlined top piece or cap and that of the vehicle may constitute apayload, space capsule or an explosive head (not shown).

When the payload is heavy or the rocket vehicle is designed to travellong distances in space and therefore must attain considerableacceleration at launch, it is customary to employ two or more boosters,symmetrically positioned with respect to the space vehicle in order toprovide the necessary increase in jet power at takeoff. The main rocketis filled with solid propellant material (not shown) of well-known type,each stage, beginning with the lowest, being ignited in order, usuallyon command from the ground.

The boosters 8, 9 furnish the necessary extra lifting power at blast offand when the main vehicle has reached a predetermined speed or distance,the fastening devices 10 are disconnected or destroyed, to permit theboosters to fall away.

It has been found on occasion that when one or more of the boosters isnot functioning satisfactorily, either just before or at the time oflaunch, this would cause a dissymmetry of the delivered power whichmight prevent the space vehicle from lifting from its pad or at leastchange its orientation. It has been the practice to secure the spacevehicle to the pad by hold down devices (not shown) which are releasedwhen it is assured that all of the boosters, as well as the rocketmotor, are all functioning. But the main difiiculty has been todeactivate all of the boosters when one has failed during this period orduring the short period after release but before the rocket has actuallyleft the launching pad.

Whereas in the prior booster construction a single solid propellant wasnormally used, in accordance with my invention, I employ two differentpropellants, one within the other, the inner propellant beingconstituted of an oxygen-poor solid material and the outer propellantbeing formed of the standard oxygen-containing slow-burning explosive.The booster may take a cylindrical shape as shown, in which case thedifferent propellants take the form of two hollow concentric cylinders11, 12 (FIG. 2), cast in tight contact with one another and leaving acentral longitudinal bore 13. The casting process can be accomplished bythe use of mandrels as is well-known in the art. The casing of thebooster, indicated at 14, is made of steel sufficiently thick towithstand the combustion of the contained propellants. The upper end ofthe casing 14 is rounded or pointed; actually shown as a hemisphere inorder to give a streamline effect. The lower end of the booster (shownin FIG. 1) constitutes a flat sheet of metal of approximately the samethickness as the casing and is provided with openings which arepositioned directly below the propellants 11, 12 and to which nozzles 15are attached. The main space vehicle has similar nozzles 16 as is alsoindicated in H6. 1 through which the jet stream is propagated from eachof the various charges of propellants. It will be understood that theshowing of the interior of the rocket 1 and the lower portions of therocket, also of the boosters 3 and 9 including the pad on which theyrest is purely diagrammatic and the actual launching structure is notshown.

The propellant body I1 is considerably thinner than that of the outerbody 12 and these bodies are in intimate contact with one another. Thecylinder 12 may constitute a heterogenous mixture of several chemicals,for example, a mixture of oxidizing crystals of perchlorate in a matrixof organic plasticlike fuel such as asphalt which embodies its ownsource of oxygen and therefore will support combustion. The innercylinder may be constituted of the same ingredients except that thepercentage of the oxidizing crystals of perchlorate is reduced to anamount that, in the absence of an additional source of oxygen, thepropellant will not support combustion. Both propellants or equivalentmaterial do or should lend themselves readily to being cast in place soas to fill up all the space within the interior of the casing 14 exceptthe opening 13. As stated hereinbefore, this may be accomplished by theuse of properly sized and positioned mandrels. The thickness of theoverlay II will depend upon the burning rate of the propellant and thedesired holddown time. A layer of propellant approximately 0.8 inchthick has been successfully employed and cast within a body 12 ofconsiderably greater thickness.

The upper end of the casing 14 is provided at the center with areentrant neck 17 having an opening 18 extending through the neck. Thisopening may be threaded as indicated at 18 to receive an injector plug19 having a downwardly extending threaded portion 20. The neck of theplug is rounded at the top which fits a similarly curved surface at theupper end of the casing in order to effect a tight seal when the plug isscrewed into the neck. There is a horizontal opening 21 extending partway through the plug 19. This opening is in communication with avertical passageway which terminates in a nozzle 22. The latter extendsa short distance into the central opening 13, and preferably, is flaredoutwardly at the edges. The horizontal portion 21 of the opening in theplug is pro vided with screw threads which receive the threaded end of aheavy copper tubing 23. This tubing may bend downwardly, as shown, andis provided with a shutoff valve 24 and from thence passes into a tank25 containing liquid oxygen in any convenient form, such as nitrogentetroxide. At the end nearer the plug 19, there is a squibactuatedvalve, termed in the trade an explosive bolt" and indicated at 26, thepurpose of which is abruptly to shut off the conduit 23 and thusdisconnect the source of oxygen from the plug when a emergency arises.This explosive bolt is provided in accordance with one of the aspects ofmy invention and its actual construction and operation are well known inthe art. Thus, assuming that the valve 24 is open and the bolt 26 isintact, i.e. unexploded, the oxgen-containing fluid from the tank 25will flow through the conduit 23 and thence through the plug 19 into thecentral bore 13. This gas will supply the oxygen-poor propellant 11 withthe necessary ingredient to cause the propellant 11 at least slowly tosupport combustion. The igniting impulse may be provided by anelectrically energized pyrogen unit 27 in each unit, of well-known typewhich, when used in connection with the usual nozzle plugs (not shown)satisfactory ignition of the overlay propellant can be assured. All ofthe boosters are given an electrical stimulus at one and the same time.The oxygen-containing mixture is introduced into the central boreimmediately prior to the liftoff and assuming that the propellant 11 hasbeen duly ignited in the presence of the supplied oxygen, the resultingcombustion will begin to burn through the propellant overlay or cover,and within a short time, will expose the surface of the oxygen-richpropellant 12. This time could be of the order of a few seconds,depending on the thickness of the overlay. The main charge 12 will thenproduce the propelling gas which, together with that obtained from thefirst stage of the space vehicle, will issue through the nozzles 15, 16(FIG. 1) to attain the necessary power for liftoff. For maximumefficiency, the overlay should be designed to burn out simultaneouslythroughout the motor. Maximum thrust will be necessary for liftoff andthis cannot be achieved until all of the overlay propellant has beenconsumed and the base propellant 12 has been exposed. However, shouldany one of the boosters fail to ignite, not withstanding having beensupplied with the oxygen containing gas, the bolt 26 can be exploded byelectrical impulse to close the valves simultaneously in all of thesupply lines to the boosters and the propellant 11, having becomestarved for oxygen, will cease to be active and thus will fail touncover any part of the surface of the propellant 12. Thus, the symmetryor balance of the thrust power about the space vehicle is maintained andthe vehicle would, of itself, not have had sufficient power to lift fromthe pad. Accordingly, the explosive stages indicated at 2, 3 and 4 andthe costly payload are saved.

From the foregoing, it is evident that l have invented an improvedbooster or booster assembly in which the functioning of all the boostersis assured during the launching operation and complete control of theoperation of the boosters as a whole is accorded from the ground. inthis manner, symmetry of the lifting power of the boosters in theaggregate is assured, so that the space vehicle will not deviate fromits proper position and course as it leaves the launching pad.

I clairn: 1. A et booster for a space vehicle, said booster comprising acasing containing a plurality of propellants in layer form in overlyingcontiguous relation, the propellant overlying the other being of amaterial which is oxygen-poor and will burn only in the presence ofoxygen, and the propellant over which the oxygen-poor propellantoverlies being of a material which is oxygen-rich and will supportcombustion when ignited, means for supplying the overlying propellantwith oxygen to cause the layer to burn through and expose at least aportion of the overlaid propellant whereby the oxygen'rich layer'iscaused to burn and produce jet action, and means including an explosionoperated valve for shutting off the supply of oxygen to the overlyingpropellant before the overlaid layer has been exposed in order to stopcombustion of the overlying propellant and prevent the overlaid layerfrom burning whereby the booster ceases immediately to operate.

2. A jet booster for a space vehicle, said booster comprising: acylindrical casing containing a plurality of propellants of cylindricalconfiguration in layer form in overlying contiguous relation fittedwithin the casing, the propellant overlying the other being of amaterial which is oxygen-poor and will burn only in the presence ofoxygen, and the propellant over which the oxygen-poor propellantoverlies tightly surrounding the oxygen-poor propellant and being of amaterial which is oxygen-rich and will support combustion when ignited,an axial opening extending through the oxygen-poor propellant, saidcasing having a threaded reentrant portion, a plug having a threadedneck for entering said portion and being screwed thereto, said plugbeing provided with a passageway extending from the exterior of the plugas far as the axial opening in the oxygen-poor propellant, and a nozzlemember extending from the exit of said passageway for a short distancealong said opening, means for supplying oxygen through said plug andnozzle into said opening of the overlying propellant to cause the layerto burn through and expose at least a portion of the overlaid propellantto the hot gas evolved by the burning of the overlying oxygen-poorpropellant whereby the oxygenrich layer is caused to burn and evolve gaswhich when ejected from the rear of the booster provides a sustained jetstream, and means for shutting off the supply of oxygen to the overlyingpropellant before the overlaid layer has been exposed in order to stopcombustion of the overlying propellant and prevent the overlaid layerfrom burning whereby the booster ceases immediately to operate.

2. A jet booster for a space vehicle, said booster comprising: acylindrical casing containing a plurality of propellants of cylindricalconfiguration in layer form in overlying contiguous relation fittedwithin the casing, the propellant overlying the other being of amaterial which is oxygen-poor and will burn only in the presence ofoxygen, and the propellant over which the oxygen-poor propellantoverlies tightly surrounding the oxygen-poor propellant and being of amaterial which is oxygen-rich and will support combustion when ignited,an axial opening extending through the oxygen-poor propellant, saidcasing having a threaded reentrant portion, a plug having a threadedneck for entering said portion and being screwed thereto, said plugbeing provided with a passageway extending from the exterior of the plugas far as the axial opening in the oxygen-poor propellant, and a nozzlemember Extending from the exit of said passageway for a short distancealong said opening, means for supplying oxygen through said plug andnozzle into said opening of the overlying propellant to cause the layerto burn through and expose at least a portion of the overlaid propellantto the hot gas evolved by the burning of the overlying oxygen-poorpropellant whereby the oxygen-rich layer is caused to burn and evolvegas which when ejected from the rear of the booster provides a sustainedjet stream, and means for shutting off the supply of oxygen to theoverlying propellant before the overlaid layer has been exposed in orderto stop combustion of the overlying propellant and prevent the overlaidlayer from burning whereby the booster ceases immediately to operate.